Knife sharpening mechanism for cutting machines



Jan. 9, 1951 F. G. CLARK 2,537,208

KNIFE SHARPENING MECHANISM FOR CUTTING MACHINES Filed Oct. 13, 1947 3 Sheets-Sheet 1 IN V EN TOR.

Jan. 9, 1951 G] CLARK 2,537,208

KNIFE SHARPENING MECHANISM FOR CUTTING MACHINES Filed Oct. 15, 1947 3 Sheets-Sheet 2 1951 F. G. CLARK KNIFE SHARPENING MECHANISM'FOR CU'FlING MACHINES 5 Sheets-Sheet 3 Filed Oct. 13, 1947 IN VEN TOR.

Jade/ 1M 6}. (7x775; MW

0&0 2 /2 Q95 Patented Jan. 9, 1951 UNITED KNIFE SHARPENING MECHANISM FOR CUTTING MACHINES Frederick G. Clark, Buffalo, N. Y., assignor to Eastman Machine Company, Bufialo, N. Y.

Application October 13, 1947, Serial No. 779,622

13 Claims.

This invention relates to knife sharpening mechanisms for cutting machines, and more particuiarly to improvements in sharpening mechanisms for portable cutting machines of the type commonly used for cutting cloth and other sheet materials, comprising a vertically reciprocating knife having a substantially vertical cutting edge, which can be caused to follow a desired pattern or line of cut in a lay of cloth or other material by appropriately moving and guiding the machine about on the supporting table for the material.

Cutting machines of this type have been equipped with knife sharpening mechanisms comprising grinding means or elements which are power driven for performing their sharpening action and are moved or shifted, either manually or by motor driven mechanism, up and down along the knife edge so as to sharpen the edge throughout its whole effective length.

One of the objects of the invention is to provide a sharpening mechanism of the sort mentioned of improved practical and desirable construction.

Other objects of the invention are to provide a sharpening mechanism of the sort mentioned with efiicient traversing means of improved construction for causing the knife grinding means to move or travel lengthwise to and fro along the knife edge; to provide a simple, reliable and durable traversing mechanism of novel construction which, in action, causes the grinding means to travel from an inactive, initial position adjacent one end of the knife in one direction along the knife edge, and then return to, the initial position in which the sharpening mechanism is automatically arrested or thrown out of action; also to provide a traversing mechanism of this character which can be readily adapted to change the length of the traversing travel of the grinding means along the knife edge as may be required for sharpening knives of different lengths which may be used in the machine; or in accordance with changes in the length of the stroke of the reciprocating knife of one or anand reliable in operation and will preclude lll'leven grinding of different portions of the knife edge.

Further objects and advantages of the men; tion will appear from the following specification "oftliepreferred embodiment of .the invention shown in the accompanying drawings, and the novel features of the invention are set forth in the appended claims.

In said drawings:

Fig. 1 is a side elevation, partly in section, on a reduced scale, of a cutting machine equipped with automatic knife sharpening mechanism embodying the invention, showing the position of parts when the sharpening mechanism is out of action with the grinding means in their initial uppermost position;

Fig. 2 is an enlarged, front or transverse sectional elevation of the sharpening mechanism on line 2-2, Fig. 1.

Fig. 3 is a horizontal sectional view thereof on line 3-3, Fig. 2.

'Fig. 4 is a transverse, sectional elevation of the sharpening mechanismon line 4-4, Fig. 3. Fig. 5 is a longitudinal, sectional elevation of the machine on line 5-5, Fig. 2, showing the position of the parts when the grinding means are at the limit of their downward travel.

Fig. 6 is a sectional plan view of the sharpen-'- ing mechanism on line 66, Fig. 2.

Fig. 7 is a plan view, partly in horizontal section thereof on line 1-1, Fig. 2. Fig. 8 is a transverse, sectional elevation there of on line 88, Fig. 6, showing the normal position of the starting device for the sharpening mechanism when the sharpening mechanism is out of action.

Fig. 9 is a view similar to Fig. 8 showing the starting device in position for operating the sharpening mechanism.

Fig. 10 is a sectional plan view on line llli!l, Fig. 8, showing the normal position of, the start-,- ing device when the sharpening mechanism is out of action.

Fig. 11 is a similar view on line I, Fig. 9

showing the position of the starting latch for causing downward travel of the grinding means.

The cutting machine and its knife sharpening mechanism, except as hereinafter described, may be of known or other suitable construction. As herein disclosed, the machine comprises the usual base 28 adapted to rest and be moved about on the supporting table for the lay of material to be cut; an upright, slender standard 2! rigidly secured on and rising from the base and sup porting the stationary frame or portion 22 of the electric motor which reciprocates the knife 23 in a vertical guide at the front of the stand ard through suitable drive mechanism includf-' ing a crank or fly wheel 24 on the front end of the horizontal rotor shaft of the motor, a pit man 25 connecting the crank wheel to a slide or crosshead (not shown), to which the upper end of the knife is suitably and removably attached; the presser foot 26 on the lower end of a guard bar 21 which extends vertically in front of the knife and is suitably mounted for vertical adjustment on the machine to set the presser foot at different levels according to the thicknesses of different lays or piles of material.

In the machine as illustrated in the drawings, the knife is sharpened by grinding means of known type comprising two narrow abrasive belts 01' bands 30 and 3i which are disposed at opposite sides of the knife to travel crosswise of the knife in sharpening contact with opposite sides of the knife edge, around front drive pulleys 32 and 33 and rear spring-actuated belttensioning pulleys 34 and 35, the belts being power driven by the knife operating motor. The pulleys for the grinding belts are carried on the under side of a carriage 35 arranged to move or travel up and down lengthwise of the knife edge to enable the belts to sharpen the knife edge throughout its full length. The grinding belts or elements together with their driving mechanism and other parts of the sharpening mechanism may be mounted on a supporting housing or cover piece 35 which is stationarily but removably secured in place on the motor frame 22 at the front of the machine and serves to conceal the crank wheel 24 and other parts of the knife operating and sharpening mechanisms. The grinder carriage may be mounted and guided in its up and down movements and, the grinding belt means constructed and mounted on the carriage as more fully described in Patent No. 2,183,786, issued December 19, 1939, to Eastman Machine Company, assignee. While the sharpening mechanism of this invention preferably employs flexible belt grinding means, such as disclosed, the invention is not limited thereto and different grinding elements or means may be employed.

The drive mechanism for the grinding belts or elements, as shown in the drawings, is constructed as follows. The belt drive pulleys 32 and 33 are fixed on the lower ends of two vertical shafts 45 and 4| which rotate but are held from axial movement in suitable bearings on carriage 36, so as to move up and down with the carriage. .Said shafts extend up into the housing 38 and are movable axially through, but caused to rotate with intermeshing pinions 42 and 43, Figs. 2 and 3, which are held from axial movement in suitable bearings in the lower end of housing 38, and are oppositely rotated by a pinion 44 on the lower end of a vertical shaft 45, Figs. 4 and 5, rotatable in suitable bearings in the housing. A

' spiral gear train 46, 4?, 48 operatively connects the upper portion of shaft 45 with the shaft of a wheel 49, Figs. 2 and 6, which is adapted to be moved into and out of contact with crank wheel 24 to be driven thereby. For this purpose the shaft 50 of wheel 49 may be rotatably supported in a bearing in a bell crank lever i pivoted on a stud 52 which is fixed in housing 38 and forms the axle for the idler spiral gear 41. A spring 53, Fig. 2, acting between one arm of lever 5i and an opposing portion of housing 38 tends to swing said lever about its pivot to press wheel 49 into contact with a frictional tire or peripheral band on crank wheel 24, whereby when wheel 49 is pressed against said tire, it is driven, and through the described gear trains, shafts and pulleys drives the grinding belts 33 and 3!. 54 is an adjusting screw engaging the outer end of spring 53 for regulating the driving pressure of wheel49 against the crank wheel.

The belt pulley shafts 4D and 4| are preferably of square or polygonal shape in cross section, and slidably engage in correspondingly shaped axial holes in their driving pinions 42, 43, and each shaft is held in intended axial position from whipping or lateral motion by a cylindrical bushing 55 (Fig. 2) secured on its upper end and arranged to revolve and slide axially in a vertical guide tube 56 suitably mounted stationarily in housing 38. This arrangement provides much more durable connections between the pulley shafts and their driving pinions, and is more economical to produce than the usual splined arrangement of pinions on shafts as by means of keys in the pinions slidably engaging in longitudinal keyways in the shafts.

An arm of lever 5| is pressed by spring 53 against the upper end of a push rod 51 which is slidable vertically in suitable guides 58 in housing 38 with its lower end projecting below the housing in position to be engaged by grinder carriage 36. When the grinder carriage is moved to its upper, initial position, it raises push rod 5'! and shifts lever 5| against the action of its spring 53 to move and hold driven wheel 49 out of contact with crank wheel 24 as shown in Fig. 2, thus stopping operation of the sharpening mechanism. When the sharpening mechanism is started to sharpen the knife, the grinder carriage is lowered, as later explained, and permits push rod 5'! to. descend and allow driving engagement of wheel 49 with the crank wheel, as shown in Fig. 4.

' The traversing mechanism for producing the up and down or to and fro travel of the grinder carriage 35 and grinding elements or belts along the knife edge is preferably constructed as fol lows. 60 represents a screw shaft, having crossing right and left hand screw threads, which is journalled to rotate but held from axial move- ,ment in suitable bearings (ii, in grinder carriage 36 so as to move up and down with the carriage. Intermeshing pinions 62 and 63 secured on the lower portions of said screw shaft and the belt pulley shaft 4|, in a chamber in carriage 36, see Figs. 2 and '7, causes rotation of the screw shaft when the sharpening mechanism is in operation for driving the grinding belts. Screw shaft 60 fextends vertically up through housing 38 and passes through two nuts 64 and 65, one having a left hand'thread engaging the left hand thread of the shaft, and the other a right hand thread engaging the right hand thread of the shaft. These nuts are held from axial movement relatively to the screw shaft between suitable end bearings 66 and 6'1 on housing 38, and preferably an anti-friction thrust bearing 68 surrounding the shaft between the adjacent inner ends of the nuts. By holding one nut, as 64, from rotation, while leaving the other free to rotate, the screw shaft rotating in the stationary nut is moved axially downwardly, whereas if the first nut is left free and the second nut is held from rotation, the screw shaft is moved axially upwardly. When both nuts are left free to rotate, there is no endwise movement of the screw shaft.

For the purpose of thus holding or freeing the nuts, preferably a starting latch device or element I0 is arranged to slide horizontally crosswise relatively to the screw shaft in a suitable guide H on housing 38 and is provided at its outer end with' an operating knob or handle l2. Normally, or

when the sharpening mechanism is not in operation, this latch device is held inanouter position, shown in Figs. 8 and 10, by-a spring 13 surrounding the latch between its guide and the handle 12, in which position adog or detent M on the latch device is held in engagement with external teeth 15 on the nut G5 and holds said nut from rotation. By shoving the latch device inwardly against the action of its spring to the position shown in Figs. 9 and 11, the dog M is disengaged from the teeth of nut 65, and a second dog or detent 16 on the latch is engaged with external teeth I! on the lower nut 64, thus freeing the nut 65 for rotation and holding the nut ts from rotation. When the starting element or device i is pushedinwardly to start operation of the sharpening mechanism, it is releasably' held in its inward position, against theaction of its spring 13, by a locking member 18 which, as shown, is slidable vertically ina guideway 18a in the housing and has, at its lower end, a lateral projection "i9 extending beneath the lower edge of latch element 10, see Figs. 5, 8 and 9. This projection is held upwardly against the bottom edge of element latch 70 by a spring 8|], Fig. 5, which surrounds the screw shaft between its bearing 66 and a laterally projecting upper end portion 8| of the lock member, through which latter the screw shaft passes, so that when the latch is pushed to its inner position, projection 19 will spring upwardly into engagement with a shoulder 82 on the bottom of latch device Til asshown in Fig. 9 and hold the latch device in its inner position in which it holds the nut 64 from rotation. When the sharpening mechanism is out of operation or inactive with the grinder carriage in its uppermost initial position, the latch device 70 will be held by its spring 73 in its normal outer position shown in Fig. 10 and hold the upper nut 65 from rotation.

In order to start the sharpening mechanism the starting latch element 10 is pushed inwardly. As the element is moved inwardly, there is a neutral position in which both dogs 74 and I6 are disengaged from both nuts 64, 65 (the dogs being spaced sufiiciently apart to permitthis) which leaves both nuts free to rotate. This allows spring 53 to actuate bell crank lever to force the driven wheel 49 into contact with crank wheel 24 and force push rod 5'! down, thus moving the parts into the position shown in Fig. 4, and starting the sharpener drive mechanism and rotation of the screw shaft 60. Further movement of starting element ill to its inner position frees the upper nut 65 and holds the lower nut 64 from rotation, thereby causing downward travel of the screw shaft and grinder carriage.

Since the starting latch is held in its inner position by the lock 18, the downward travel of the grinder carriage and the screw shaft will continue until a reversing member or sleeve 85 secured on the upper end of the screw shaft engages the upper end portion 8| of the lock member 18 and depresses the lock, thereby releasing the starting latch device, which will then be moved outwardly by itsspring 13 and free the lower nut 64 and hold the other nut 65 from rotation, thereby causing the return upward movement of the screw shaft and grinder carriage until the carriage in the final portion of its upward movement raises push rod 51 and operates bell crank lever 5| to throw driven wheel 49 out of driving engagement with the crank wheel thereby stoppingthe opera tion of the sharpening mechanism with the grinder carriage in its uppermost initial position.

" Ihe reversing sleeve 85 is axially'adjustableon of the type disclosed herein to change the length of stroke of the reciprocating knife as most suit: able for cutting materials of diiferent character. Also such machines are made so that the machine may be provided with a standard of one or another length and with a knife of appropriate length, to better adapt the machine for cutting material piles or lays of different heights. By using a reversin sleeve such as described of appropriate length or by appropriately adjusting the sleeve axiallyto different positions on the screw shaft, very simple and efficient means are provided for causing the return or upward travel of the grinding means when, in its downward travel, it has reached the lower end of the knife, regardless of the length of the knife or the length of the reciprocating strokes of the knife. Furthermore the reversing sleeve being cylindrical and rotatable and movable axially in a guide tube 8? effectually holds the upper end of the screw shaft from whipping or lateral motion during the operation of the sharp ening mechanism.

Preferably the machine is equipped with safety means to prevent operation of the sharpening mechanism except after the presser foot 20' has been set in its lowermost position so as thus to prevent the presser foot from interfering with the downward travel of the grinding means with possible injury to the sharpening mechanism: For this purpose the presser foot supporting bar 2'! which extends past andadjacent the inner end of latch device ll] is provided with a notch 90,

Figs. 1, 10 and 11, in the side thereof facing the latch device. When the presser foot is in its lowermost position, this notch will be located opposite and adapted to receive the inner end-of the latch device, thus permitting full inward move ment of the latter to the position shown in Fig. 11 to cause downward travel of the grind-ng means. In any other adjustment of the presser foot, its supporting bar 27 will be engaged by and-prevent the necessary inward movement of the latch device to start operation of the sharpening mechanism.

I claim:

1. In a knife sharpening mechanism for cut ting machines having a knife, driven grinding means for the knife edge, and a movable support; ing carriage for the grinding means, the proved traversing mechanism for effecting travel of the grinding means to and fro along the knife edge comprising a rotatable screw shaft having right and left hand threads and movable axial- 1y for causing travel of said carriagetwo nuts held from axial movement and operatively en-i gaging respectively the right and left "hand threads of said shaft, latch means operable. to hold one nut from rotation while leaving the sec-- ond nut free for moving said screw shaft axially in one direction, and means actuated by the longitudinal movement of said screw shaft for shifting said latch means to free said first nut and hold the second nut from rotation'for'niov ing said'screw shaft axially in the opposite direction.

1 2. In a knife sharpening mechanism for cutting machines having a knife, grinding means for the knife edge and drive means therefor, and a movable supporting carriage for said grinding means, theimproved traversing mechanism for effecting travel of said grinding means to and fro along the knife edge comprising a screw shaft rotated by said driving means and having crossing right and left hand screw threads and movable axially for causing travel of said carriage, two .nuts held from axial movement and operatively engaging respectively the right and left hand threads of said shaft, latch means operable to hold one nut from rotation while leaving the second. nut free for moving said shaft axially in one direction, and means mounted on said shaft and adjustable lengthwise thereof to operate upon a predetermined length of said axial movement of said shaft to actuate said latch means to free said first nut and hold said second nut from rotation to cause to return axial movement of said shaft.

3. In. a .knife sharpening mechanism for cutting machines having a knife, grinding means for the knife edge and drive means therefor, and a movable supporting carriage for said grinding means, the improved traversing mechanism for effecting travel of said grinding means to and fro along the knife edge comprising a rotatable screw shaft having crossing right and left hand screw threads and movable in the direction of its axis, means operated by said driving means for rotating said screw shaft, two rotatable nuts held from axial movement and operatively engaging respectively said right and left hand threads, a latch device operable to hold one or the other of said nuts from rotation in different positions of said latch device, said latch device in its normal position holding one nut from rotation, said latch device being movable to a different position to free said nut and hold said second nut from rotation for causing axial movement of said shaft in one direction, a locking device for releasably locking said latch device in said different position, and a part operable upon a predetermined axial movement of said shaft to actuate said locking device to release said latch device, said part being adjustable to vary the movement required to actuate said locking device, said latch when released being returned to normal position to free said second nut and hold said first nut from rotation for causing return axial movement of said shaft to its initial position.

4. In a knife sharpening mechanism for cutting machines having a knife, grinding means for the knife edge and drive means therefor, and a movable supporting carriage for said grinding means, the improved traversing mechanism for effecting travel of said grinding means to and fro along the knife edge comprising a rotatable screw shaft having crossing right and left hand screw threads, means operated by said driving means for rotating said screw shaft, two rotatable nuts held from axial movement and operatively engaging respectively said right and left hand threads, a latch device having spaced dogs arranged to hold one or the other of said nuts from rotation in different positions of said latch device, spring means normally holding said latch device in position to hold one nut from rotation, said latch device being movable against the ac- .tion of its spring to free said nut and hold said second nut from rotation for causing axial movement of said shaft in one direction, means for re-- leasably locking said latch device against the action of its spring during said axial movement of the shaft, and means operable upon a predetermined axial movement of said shaft to actuate said locking means to release said latch device, said latch device when released being returned by its spring to its normal position to free said second nut and hold said first nut from rotation for causing return axial movement of said shaft to its initial position.

5. An improved traversing mechanism for effecting to and fro travel of the knife grinding means of sharpening mechanism for a cutting machine according to claim 3, in which said part for actuating said locking device is adjustably connected with said screw shaft to actuate said locking means upon different predetermined axial movements of said screw shaft.

6. An improved traversing mechanism for effecting to and fro travel of the knife grinding means of sharpening mechanism for a cutting machine according to claim 3, in which a sleeve removably secured .on said screw shaft actuates said locking means, said sleeve being of one or another length to actuate said locking means upon different predetermined axial movements of said screw shaft.

7. In a knife sharpening mechanism for cutting machines having a knife, grinding means for the knife edge and drive means therefor, and

a movable supporting carriage for said grinding means, the improved traversing mechanism for effecting travel of said grinding means to and fro along the knife edge comprising a rotatable screw shaft having crossing right and left hand screw threads, means operated by said driving means for rotating said screw shaft, two rotatable nuts held from axial movement and operatively engaging respectively said right and left hand threads, a latch device having spaced dogs arranged to hold one or the other of said nuts from rotation in different positions of said latch device, spring means normally holding said latch device in position to hold one nut from rotation, said latch device being movable against the action of its spring to free said nut and hold said second nut from rotation for causing axial movement of said shaft in one direction, means for releasably locking said latch device against the action of its spring during said axial movement of the shaft, and a member secured to and movable with said screw shaft for actuating said locking means to release said latch device for action by its spring upon a predetermined axial movement of said screw shaft, said latch device when released being shifted by its spring to release said second nut and hold said first nut from rotation for causing return axial movement of said shaft to its initial position.

8. In a knife sharpening mechanism for cutting machines having a knife, grinding means for the knife edge and drive means therefor, and a movable supporting carriage for said grinding means, the improved traversing mechanism for effecting travel of said grinding means to and fro along the knife edge, comprising a rotatable screw shaft secured at one end against axial movement thereof to said carriage and having crossing right and left hand screw threads, means operatively connected with said drive means for rotating said screw shaft, two rotatable nuts held from axial movement and operatively engaging respectively said right and left hand threads, between-the ends of said screw shaft, a cylindri cal sleeve on the oppos'te end of said screw shaft,

a stationary tube in which said sleeve is axially movable and guided, a latch device operable to hold one or the other of said nuts from rotation, said latch device in one position Eeaving one nut free and holdng the second nut from rotation to cause axial movement of said screw shaft in one direction, a locking device for releasably locking said latch device in said position, said locking device being actuated by said sleeve upon a predetermined ax al movement of said shaft for releasing said latch device, and means which shifts said latch device when released to free said second nut and hold said first nut from rotation for causing return axial movement of said screw shaft.

9. In a knife sharpening mechanism for a cutting machine having knife grinding means, a movable supporting carriage for said grinding means, and traversing mechanism for effecting travel of said carriage and grinding means to and fro along the knife edge, the improved drive mechanism for said grinding means including a rotatable driving shaft for said grinding means movable axially thereof with said carriage, said shaft being of polygonal cross section, a wheel having an axial hole in which said shaft is axially movable but held to rotate with said wheel, a cylindrical member connected to the upper portion of said shaft throughout the axial movement thereof, and a stationary tube in which said cylindrical member is axial y movable with the shaft and guided while rotating with said shaft.

10. In a knife sharpening mechanism for a cutting machine having knife grinding means, a movable supporting carriage for said grinding means, and traversing mechanism for effecting travel of said carriage and grinding means to and fro along the knife edge, the improved drive mechanism for said grinding means including a rotatable driving shaft for said grinding means movable axially thereof with said carriage, said shaft being of polygonal cross section, a wheel having an axial hole in which said shaft is axially movable but held to rotate with said wheel, a cylindrical sleeve on the free end of said shaft, and a stationary cylindrical tube in which said sleeve is rotatable and axially movable with-the shaft throughout the axial movement thereof and guided for preventing lateral movement of said shaft.

11. An impoved traversing mechanism for effecting to and fro travel of the knife grinding means of sharpening mechanism for a cutting machine according to claim 1, which includes a 10' cylindrical member secured to said screw shaft, and a stationary guide tube in which said cylindrical member is rotatable and movable axially for preventing lateral motion of said screw shaft.

12. In a knife sharpening mechanism for cutting machines having a knife, driven grinding means for the knife edge, a movable supporting carriage for the grinding means and a presser foot for the work, the improvement comprising mechanism which produces travel of said grinding means along the knife edge and includes a starting element movable to a starting position to start operation of said sharpening mechanism, and a presser foot support which is adjustable to change the position of said presser foot relatively to the knife, said support having a notch therein which, in a predetermined position only of said presser foot, is located opposite said starting element and allows movement of the latter to said starting position.

13. In a knife sharpening mechanism for cutting machines having a knife, grinding means for the knife edge and drive means therefor, and a movable supporting carriage for said grinding means, the improved traversing mechanism for effecting travel of said grinding means to and fro along the knife edge comprising a rotatable screw shaft having crossing right and left hand screw threads and movable in the direction of its axis, means operated by said driving means for rotating said screw shaft, two rotatable nuts held from axial movement and operatively engaging respectively said right and left hand threads, a latch device having spaced dogs arranged to hold one or the other of said nuts from rotation in different positions of said latch device, means for yieldingly urging said latch device into one of said positions, a locking member for holding said latch device in another position against the action of said yielding means, and means for releasing said locking member to permit said yielding means to return said latch device to said first position.

FREDERICK G. CLARK.

REFERENCE S CITED The following references are of record in the file of this patent:

UN I'ILED STATES PATENTS Number Name Date r 1,896,752 Raule Feb. 7, 1933 2,060,197 Greenbaum Nov. 10, 1936 2,183,787 Clark Dec. 19, 1939 2,295,654 Gury Sept. 15, 1942 2,423,570 Steiner July 8, 1947 

